1. Field of the Invention
The present invention relates to a measuring nail for use in measuring a thickness at which roadbed materials of concrete or asphalt pavement are evenly laid on a roadbed for paving a road therewith, or a thickness at which ballast, crushed stone and cobble stone are evenly laid on the roadbed for forming a basic concrete or for installing secondary concrete products.
2. Description of the Prior Art
For paving a road by laying pavement materials evenly over a roadbed, for example, the roadbed is first corrected in the unevenness and then is rolled and compacted with a machine such as a macadam roller, a tired roller, a hand roller or a vibration roller. Thereafter, wooden measuring piles or iron measuring piles are embedded in the rolled and compacted roadbed in such a manner that their upper portions can project from the roadbed by a certain height and also their top surface can be flush with an expected height of the roadbed.
Taking the work of laying asphalt evenly over the roadbed for instance, vehicles such as a motorized grader and an asphalt finisher are run over the asphalt to spread the asphalt uniformly. When a worker spreads the pavement material by using those vehicles, the length of projecting portions of the embedded piles serves as a guide for his paving the road with the pavement material at a uniform thickness. It is noted that the spreading of the pavement material may be carried out with hands, instead of the vehicles.
However, this conventional type measuring pile mentioned above can often be pushed down on and pulled up from the roadbed by a blade of the motorized grader, a foot of the worker or a tire of a pavement material carrying dump car. The pile pulled out from the roadbed have to be readjusted in its vertical level at much expense in time and effort or energy, while it is embedded again in the roadbed.